Date: Wed, 11 Mar 2009 22:00:03 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r189708 - head/sys/kern Message-ID: <200903112200.n2BM03Q2007742@svn.freebsd.org>
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Author: rwatson Date: Wed Mar 11 22:00:03 2009 New Revision: 189708 URL: http://svn.freebsd.org/changeset/base/189708 Log: When writing out updated pollfd records when returning from poll(), only copy out the revents field, not the whole pollfd structure. Otherwise, if the events field is updated concurrently by another thread, that update may be lost. This issue apparently causes problems for the JDK on FreeBSD, which expects the Linux behavior of not updating all fields (somewhat oddly, Solaris does not implement the required behavior, but presumably our adaptation of the JDK is based on the Linux port?). MFC after: 2 weeks PR: kern/130924 Submitted by: Kurt Miller <kurt @ intricatesoftware.com> Discussed with: kib Modified: head/sys/kern/sys_generic.c Modified: head/sys/kern/sys_generic.c ============================================================================== --- head/sys/kern/sys_generic.c Wed Mar 11 21:48:36 2009 (r189707) +++ head/sys/kern/sys_generic.c Wed Mar 11 22:00:03 2009 (r189708) @@ -76,6 +76,7 @@ static MALLOC_DEFINE(M_IOCTLOPS, "ioctlo static MALLOC_DEFINE(M_SELECT, "select", "select() buffer"); MALLOC_DEFINE(M_IOV, "iov", "large iov's"); +static int pollout(struct pollfd *, struct pollfd *, u_int); static int pollscan(struct thread *, struct pollfd *, u_int); static int pollrescan(struct thread *); static int selscan(struct thread *, fd_mask **, fd_mask **, int); @@ -1128,7 +1129,7 @@ done: if (error == EWOULDBLOCK) error = 0; if (error == 0) { - error = copyout(bits, uap->fds, ni); + error = pollout(bits, uap->fds, nfds); if (error) goto out; } @@ -1183,6 +1184,26 @@ pollrescan(struct thread *td) static int +pollout(fds, ufds, nfd) + struct pollfd *fds; + struct pollfd *ufds; + u_int nfd; +{ + int error = 0; + u_int i = 0; + + for (i = 0; i < nfd; i++) { + error = copyout(&fds->revents, &ufds->revents, + sizeof(ufds->revents)); + if (error) + return (error); + fds++; + ufds++; + } + return (0); +} + +static int pollscan(td, fds, nfd) struct thread *td; struct pollfd *fds;
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